• Progress in Superconductivity
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• 제2권2호
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• pp.57-64
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• 2001

We have calculated the tunneling density of states (TDOS) of a metal/d-wave superconductor proximity junction, where the metal stands fur the normal metal, 5-wave superconductor, and d-wave superconductor. The tunneling direction is through the ab-plane of the d-wave superconductor. Because of the sign change in the order parameter experienced in the multiple Andreev reflection, there appears a finite TDOS at zero bias for duty geometry, which results in the anomalous zero bias conductance peak(ZBCP). For $d_{x2-y2}$ geometry, however, no TDOS peak appears at zero bias. We have calculated TDOS for various crystal orientation of HTSC and compared with the experimental conductance.

• Journal of Ecology and Environment
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• 제33권3호
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• pp.223-228
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• 2010

Soil microbes perform crucial roles in the nutrient cycles of forest ecosystems, by effecting the decomposition of organic matter. Enzyme activities have been used to evaluate decomposition rates, as well as microbial activities. The principal objectives of this study were to determine the activities of different soil enzymes, to compare enzyme activities at different elevations, and to elucidate the most important controlling variables for enzyme activities. We conducted a field survey at three sites in Mt. Jumbong on a monthly basis from May, 2004 to September, 2005. Enzyme activities did not change substantially over different seasons. However, the spatial differences were distinct; the lowest elevation site evidenced the lowest levels of enzyme activity. Soils at the lowest elevation were nutrient-depleted soils, and enzyme activities appeared to be affected by precipitation and temperature. However, enzyme activities in fertile soils at high elevations were associated with nutrients and organic matter. The enzyme activities detected in this study differed significantly at the three elevations, and their controlling variables also evidenced different factors.

• 한국자동차공학회논문집
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• 제4권4호
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• pp.164-170
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• 1996

Among after treatment devices which reduce exhaust gas of diesel engine, diesel oxidation catalyst(DOC) with high reduction efficiency for gaseous matter and particulate matter is now being studied actively. In this study, an experiment was conducted to analyze the effects on factors of oxidaton characteristics and conversion efficiency of DOC. We tested to estimate change of engine performance whether a 11,000cc diesel engine equipps with DOC or not. We conducted test to estimate the reduction efficiency of exhaust gas in P-5 mode, in D-13 mode of heavy duty diesel regulation mode and in somoke opacity mode for two samples and also we conducted test to analyze the effects about both exhaust gas velocities 1,100rpm and 2,200rpm

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.3.1-3.1
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• 2009

Nanotechnology has beenrapidly evolved from passive nanostructures where nanostructures with steadystructures and functions often used as parts of a product to activenanostructures which change their properties during use. Startingaround 2010, it is anticipated that researchers will cultivate expertise withsystems of nanostructures, directing large numbers of intricate components tospecified needs. One dimensional (1-D) nanostructures suchas nanowires and nanotubes are extremely attractive building blocks for nextgeneration devices because of their high surface to volume ratio and uniquesize dependent properties. In addition, their extremely high aspectratio offers researchers the potentials to build axial or radialheterostructures to integrate multiple functionality from intrinsic propertiesof the material or through interfacial phenomena. Spatialmanipulation and the ability to assemble and position nanostuructures in acontrolled matter so they are registered to define spaces is also a criticalstep toward scalable integration in high density nanodevices. In thispresentation, a generalized template directed electrodeposition with ancillaryassembly, contact will be presented to synthesize axial and radialheterostructures in cost-effective matter and these individual nanostructureswill be applied to spintronics, gas and biological sensors and thermoelectrics.

• Environmental Engineering Research
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• 제16권3호
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• pp.175-183
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• 2011

The climate of the $21^{st}$ century is likely to be significantly different from that of the 20th century because of human-induced climate change. An extreme weather event is defined as a climate phenomenon that has not been observed for the past 30 years and that may have occurred by climate change and climate variability. The abnormal climate change can induce natural disasters such as floods, droughts, typhoons, heavy snow, etc. How will the frequency and intensity of extreme weather events be affected by the global warming change in the $21^{st}$ century? This could be a quite interesting matter of concern to the hydrologists who will forecast the extreme weather events for preventing future natural disasters. In this study, we establish the extreme indices and analyze the trend of extreme weather events using extreme indices estimated from the observed data of 66 stations controlled by the Korea Meteorological Administration (KMA) in Korea. These analyses showed that spatially coherent and statistically significant changes in the extreme events of temperature and rainfall have occurred. Under the global climate change, Korea, unlike in the past, is now being affected by extreme weather events such as heavy rain and abnormal temperatures in addition to changes in climate phenomena.

• 한국과학교육학회지
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• 제21권4호
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• pp.745-756
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• 2001

이 연구는 개념변화 맥락을 제공하는 개념생태의 상호작용에 관한 사례 연구이다. 사례 연구를 통해, 개념생태를 구성하는 세 가지 특징(개념, 과거 경험, 설명일관성)의 상호작용적 맥락을 구체적으로 제시하고 그 상호작용적 특정이 개념변화를 어렵게 하는데 공헌하고 있음을 밝힌다. 이 연구의 시사점은 크게 세 가지이다. 첫째, 개념 학습을 목표로 하는 교수(teaching)는 특정 과제에 대하여 학생들의 개념생태 내에 자리잡고 있는 관련된 장소에서 출발해야 한다. 둘째, 학생들의 비일관적인 설명은 개념변화의 단서로 이용될 수 있다. 셋째, 과거 경험은 학습자를 깊이 이해하기 위해 개념생태 연구가 지속적으로 탐구해야할 영역이다.

• Ocean and Polar Research
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• 제25권4호
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• pp.653-662
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• 2003

Changes in the area of geo-ecosystem $(62^{\circ}09'S,\;58^{\circ}31'w)$ reflect climatic changes in the South Shetland Islands. Air temperature and deglaciation will increase. The ice-free space area at the SSSS 8- (ASPA 121) site has enlarged threefold during the last 21 years, thus creating conditions for inhabitation and succession. Wind, water and snow play important roles in transportation of geochemical components. They distribute nutrients, mineral substances, seeds, fragments of plants and animals, etc. Plant and animal colonization is patchy and it happens at random in an 'island' - like manner. The colonization pattern is dependant, to a high degree on physical factors. The newly uncovered ice-free areas are at first inhabited by a vascular plant known as the Deschampsia antarctica. The border of the land-oasis with Admiralty Bay is the place where the processes related to animal feeding at the sea and reproduction on the land take place. Bird colonies and pinniped lairs form centers of fertilization surrounded by high chemical gradients dependent on the direction of the flow of nutrients $(e.g.\;NH_4)$. During the last 25 years, the numbers of penguins in this region have decreased, and thus the amount of materials excreted on land has diminished. The numbers of fur seals change in multi-annual cycles, and their migration into this area is related to the E1 $Ni\~{n}o$ phenomenon. The numbers of elephant seals in the area did not change. Organic matter deposited by the sea onto the shore are a source of nutrients and deficient chemical elements on land. Mineral matter is washed out into the waters of Admiralty Bay. These processes change seasonally, and multi annually. Negative effects on the environment at Arctowski Station induced by man are slight, but noticeable nevertheless. Physical processes have the largest influence on the living conditions and distribution of plants and animals, and as a consequence, on the functioning of the geo-ecosystem in the coastal-shore zone of the Maritime Antarctic.

• Journal of Preventive Medicine and Public Health
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• 제56권5호
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• pp.449-457
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• 2023

Objectives: This study investigated the association between baseline exposures to particulate matter with a diameter <2.5 microns (PM_2.5) and subsequent temporal changes in PM_2.5 exposure with the incidence of type 2 diabetes among Royal Thai Army personnel. Methods: A retrospective cohort study was conducted using nationwide health check-up data from 21 325 Thai Army personnel between 2018 and 2021. Multilevel mixed-effects parametric survival statistics were utilized to analyze the relationship between baseline (i.e., PM_2.5-baseline) and subsequent changes (i.e., PM_2.5-change) in PM_2.5 exposure and the occurrence of type 2 diabetes. Hazard ratios (HRs) and 95% confidence intervals (CIs) were employed to assess this association while considering covariates. Results: There was a significant association between both PM_2.5 baseline and PM_2.5-change and the incidence of type 2 diabetes in a dose-response manner. Compared to quartile 1, the HRs for quartiles 2 to 4 of PM_2.5-baseline were 1.11 (95% CI, 0.74 to 1.65), 1.51 (95% CI, 1.00 to 2.28), and 1.77 (95% CI, 1.07 to 2.93), respectively. Similarly, the HRs for quartiles 2 to 4 of PM_2.5-change were 1.41 (95% CI, 1.14 to 1.75), 1.43 (95% CI, 1.13 to 1.81) and 2.40 (95% CI, 1.84 to 3.14), respectively. Conclusions: Our findings contribute to existing evidence regarding the association between short-term and long-term exposure to PM_2.5 and the incidence of diabetes among personnel in the Royal Thai Army.

• 해양환경안전학회지
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• 제25권7호
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• pp.974-981
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• 2019

미세먼지발생 문제는 커다란 사회적 문제로 대두되고 있다. 선박에서는 주 추진 동력원으로 디젤엔진을 주로 사용하고 있다. 본 연구에서는 디젤엔진에서 발생하는 미세먼지로 알려진 입자상 물질을 줄이기 위해서 디젤엔진의 후처리시스템으로 사용 중인 DPF(디젤미립자 필터, Diesel particulate filter)를 소개하고자 한다. DPF의 소재로는 Cordierite와 SiC (Silicon carbide)의 두 가지가 사용되고 있다. 본 논문에서는 SiC DPF에 사용되는 접합제의 물성 향상을 위해서 기존 접합제로 사용된 SiC 계열의 물질 대신 코디얼라이트를 사용하여 열팽창계수 변화를 통한 고온 변형에 대한 열 내구성을 평가하였으며, 접합제와 Segment 사이의 결합을 결정짓는 바탕제에 주성분인 실리카졸의 pH 변화에 따른 물성 변화를 확인하였다. 이를 기반으로 실리카 졸의 반응성을 높이기 위해 Siline계 커플링제를 첨가하거나 SiC를 일부 첨가함으로써 접합제의 물성 변화의 영향에 대해서 실험을 통하여 확인하였다.

• 한국토양비료학회지
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• 제30권4호
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• pp.370-376
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• 1997

우리나라에서 가장 많이 소비되고 있는 채소중의 하나인 무를 실험종으로 선택하여 토양중 크롬의 농도, 토양 pH, 공존중금속 첨가, 복토, 유기물처리의 요인을 변수로 하여 무의 생육상태 및 무에 의한 크롬의 흡수이행량 차이를 조사하였다. 무종자의 발아율은 크롬농도 50mg/kg에서는 발아에 영향이 없었으나 100% 이상이었으며, 250mg/kg에서는 63% 정도의 발아율을 나타내었다. 토양중에 처리된 크롬농도가 증가할수록 무의 초장, 근장, 건물량이 감소하는 경향이었으며 크롬농도 100mg/kg 까지는 대조구와 비슷하게 생육하였으나 크롬농도 250mg/kg에서 건물량의 약 45%의 생육저해가 나타났다. 토양 pH가 증가함에 따라 무로 흡수이행되는 크롬의 함량이 감소하는 역의 상관을 나타내었으며(줄기: $r=-0.803^*$, 뿌리: $r=-0.840^*$) Fe, Zn, Cu와 같은 공존이온 첨가시 무의 생육 및 흡수이행되는 크롬함량간에 유의성이 인정되지 않았다(줄기, 뿌리 P>0.1). 복토, 유기물처리를 하였을 경우 대조구에 비하여 생육상태가 진전되었으며, 복토처리시 무로의 흡수이행량은 큰 차이를 나타내지 않은 반면에 유기물 처리시 무로 흡수이행되는 크롬의 함량이 감소하는 경향이었다.